How to solve sudoku
Sudoku asks for one thing: the digits 1–9 in every row, every column and every 3 × 3 box, each exactly once. A good grid never needs a guess — every cell falls to an argument.
The arguments come in a ladder, and this page climbs its first rungs: scanning, singles, and the first of the box-and-line moves. Each is shown on a small position you can step through at your own pace.
How to play
Fill the grid so every row, every column and every 3 × 3 box holds the digits 1–9, each exactly once.
A few digits are given; the rest is deduction from what already stands.
There is exactly one solution, and it never needs a guess.
The one habit worth building from the start: work from what a digit forbids, not from what a cell might hold. A placed digit closes its whole row, column and box at once — three lines of the grid answered by one glance. Everything below is that observation, sharpened.
Scanning for hidden singles
The workhorse of every sudoku: pick a box, pick a missing digit, and let the copies of that digit already on the board cross out rows and columns until a single cell is left. No pencil marks needed — just looking in lines.
Naked singles
Scanning asks where a digit can go; this asks the opposite — what a cell can hold. When a cell’s row, column and box already show eight different digits between them, the cell has no choice left.
Pointing pairs
Sometimes a scan does not finish the job: a digit still has two or three places left in its box. But if those places all sit in one row or column, that is knowledge too — the digit claims the line without settling the cell.
No timer. Leave and come back — it’s saved.
Play today’s sudoku